Java 泛型

public class Test<T> {

    private T body;

    public T getBody() {
        return body;
    }

    public void setBody(T body) {
        this.body = body;
    }

}

public static <T>String getClassName(T t) {
    return t.getClass().getName();
}

public static void main(String[] args) {
    System.out.println(getClassName("1234"));
    System.out.println(getClassName(123));
    System.out.println(getClassName(123D));
    System.out.println(getClassName(123L));
    System.out.println(getClassName(123F));
}

java.lang.String
java.lang.Integer
java.lang.Double
java.lang.Long
java.lang.Float